Technical Field
The present disclosure relates to a vehicle seat belt system.
Related Art
Japanese Patent Application Laid-open (JP-A) No. 2001-322531 discloses a buckle device having a buckle body, with which a tongue of a seat belt becomes engaged, and a pretensioner, which causes the buckle body to move backward in an emergency. This buckle device is equipped with a shock absorbing mechanism (force limiter) that allows the buckle body to move in a direction of forward propulsion when a predetermined forward propulsion force or greater has been applied to the buckle body after the buckle body has moved backward.
Furthermore, JP-A No. 2013-18460 discloses a vehicle seat belt system where one end of webbing can be taken up by a seat belt retractor equipped with a pretensioner. The other end of the webbing is anchored via a lap outer pretensioner to an outer surface of a vehicle seat or to a vehicle body. The other end of a buckle is secured, via a force limiter having an energy absorbing (EA) function, to the vehicle body or to the vehicle seat.
Moreover, JP-A No. H10-100860 discloses a shock absorption device (force limiter) provided on the anchored side (buckle) of a vehicle seat belt.
In the conventional example disclosed in JP-A No. 2001-322531, the position of the buckle changes to a position higher than normal because of activation of the force limiter, and the position of the tongue plate engaged with the buckle also becomes higher.
When this happens, the ability of the webbing to restrain the occupant is affected, so it is not preferred that the webbing be refastened and used in a state in which the position of the buckle remains changed. In a case where the force limiter has been activated, it is preferred that this be detected and that the occupant be notified of the abnormality.
In a case where the buckle is provided with a pretensioner and a force limiter as in the conventional example disclosed in JP-A No. 2001-322531, the fact that the initiator of the gas generator becomes disconnected by an explosive in the activation of the pretensioner can be utilized to electrically detect the activation of the force limiter thereafter.
However, in a case where the buckle is not provided with a pretensioner as in the conventional examples disclosed in JP-A No. 2013-18460 and JP-A No. H10-100860, it has been difficult to detect the activation of the force limiter.